Fingerprint sensing and matching is a reliable and widely used technique for personal identification or verification. In particular, a common approach to fingerprint identification involves scanning a sample fingerprint to obtain an image thereof and storing the image and/or unique characteristics of the fingerprint image. The characteristics of a sample fingerprint may be compared to information for reference fingerprints already in a database to determine proper identification of a person, such as for verification purposes.
One class of fingerprint sensors is based on the active thermal sensing principle as described in, for example, U.S. Pat. No. 6,091,837 entitled “Sensor For Acquiring a Fingerprint” issued Jul. 18, 2000 and U.S. Pat. No. 7,910,902 entitled “Apparatus for Fingerprint Sensing” issued Mar. 22, 2011, the entirety of each of which is hereby incorporated by reference herein.
There are challenges for integrating a biometric fingerprint chipset into a biometric system on card (BSoC). One challenge is that the active side of the fingerprint sensor must necessarily be oriented in the upward direction because direct contact with the finger is needed. This orientation necessitates the use of wire-bonding where electrical contact to the active side is established by wires bonds. But wire bonding techniques have high cost, low yield, and reliability disadvantages.